Biology; Chemistry; Physics: Post your doubts here!

[usama321]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_s05_qp_4.pdf

question 3 part c(1) why will chlorine be produced here when it says aqueous sodium chloride??? no mention of concentrated

tag me please if you get the answer

 

[hira jaf]

i need guees paper for chem atp

 

[AhsanAfzal]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20O%20Level/Chemistry%20(5070)/5070_s05_qp_4.pdf

question 3 part c(1) why will chlorine be produced here when it says aqueous sodium chloride??? no mention of concentrated

chlorine is produced in aqueous sodim chloride at anode

 

[AhsanAfzal]

is the answer B?

 

[mercedes008]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_s05_qp_4.pdf

question 3 part c(1) why will chlorine be produced here when it says aqueous sodium chloride??? no mention of concentrated

Sodium Chloride is the ONLY exception to that rule. conc/dilute doesn't matter, chlorine will be discharged in both cases. the reason is kinda high level to understand, but in simple terms, it is due to the small size of NaCl lattice

 

[mercedes008]

is the answer B?

I'll ask you a question about that, do you know which meniscus do we use to check the reading, upper or lower? if you know the answer then you can figure it out

 

[AhsanAfzal]

I'll ask you a question about that, do you know which meniscus do we use to check the reading, upper or lower? if you know the answer then you can figure it out

no i dont know thats why i asked

 

[sourov97]

is the answer B?

should be A...take the lower part of the meniscus.....

 

[AhsanAfzal]

is the answer B?

the answer is A as we read meniscus from bottom. am i right?

 

[AhsanAfzal]

should be A...take the lower part of the meniscus.....

alright

 

[AhsanAfzal]

are there any answers for this imran merchant paper?

 

[HDIWAN]

tag me please if you get the answer

Sodium Chloride is the ONLY exception to that rule. conc/dilute doesn't matter, chlorine will be discharged in both cases. the reason is kinda high level to understand, but in simple terms, it is due to the small size of NaCl lattice

 

[AhsanAfzal]

explain part (d)

 

[sourov97]

explain part (d)

solution T (mixture with acid and water) is in flask and solution S (KMnO4) is in burette
(d) (i) should be colourless as T is colourless...view the reply to Danish......#9762...he also had same prob....
(ii) KMnO4 is purple, and it was added from burette untill 'just excess' volume was reached, so the colour change at end is purple/pink
hope it helps

 

[AhsanAfzal]

solution T (mixture with acid and water) is in flask and solution S (KMnO4) is in burette
(d) (i) should be colourless as T is colourless...view the reply to Danish......#9762...he also had same prob....
(ii) KMnO4 is purple, and it was added from burette untill 'just excess' volume was reached, so the colour change at end is purple/pink
hope it helps

but wouldnt fe3+ and fe2+ colours will come in the solution?

 

[sourov97]

but wouldnt fe3+ and fe2+ colours will come in the solution?

okay.....the question says that the solution T is made by dissolving the mixture R with 100 cm3 acid and then made upto 250 cm3 with distill water, both of which (acid & water) are colourless.
so even if a colour of Fe2+ or Fe3+ had exist, it will eventually fade to colourless.
the question is from june 06 Q-9...mark scheme says two option for (d) (i), colourless or green.
i am not sure why green is allowed but red-brown (Fe3+) is not, but you can always go with colourless...
hope it helps

 

[sourov97]

are there any answers for this imran merchant paper?

thanks to him, did well by gathering some of the confusing questions.
if u had a view of chem p4 form nov 01 till nov 12, u should find all those questions and find the answers in mark scheme or examiner report.

 

[AhsanAfzal]

okay.....the question says that the solution T is made by dissolving the mixture R with 100 cm3 acid and then made upto 250 cm3 with distill water, both of which (acid & water) are colourless.
so even if a colour of Fe2+ or Fe3+ had exist, it will eventually fade to colourless.
the question is from june 06 Q-9...mark scheme says two option for (d) (i), colourless or green.
i am not sure why green is allowed but red-brown (Fe3+) is not, but you can always go with colourless...
hope it helps

thnks

 

[AhsanAfzal]

one more question. will we get periodic table in atp?

 

[Kamihus]

one more question. will we get periodic table in atp?

nope and you dont need it the Mr required will be given